Sheet feeding mechanism for a small duplicating machine

ABSTRACT

The sheet feeding mechanism for a small offset duplicating machine has a sheet engaging element axially adjustable on a continuously rotating drive shaft. The engaging part of the element has an exposed face arcuately convex about the axis of rotation and two terminal sections offset from the exposed face in opposite circumferential directions. Two carrier parts of the element respectively connect the terminal sections to the shaft. One of the two carrier parts is sufficiently resilient to permit some radial movement of the associated terminal section under the deforming pressure of a sheet engaged by the exposed face, while the other carrier part is rigid enough to prevent circumferential movement of the entire face.

[ 1 Mar. 14, 1972 [54] SHEET FEEDING MECHANISM FOR A SMALL DUPLICATING MACHINE [72] Inventors: RIQQ! Mi gr St. Geotgen; Heinz Joachim Schinke, Unterkirnach; Hermann Raible, St. Georgen, all of Germany [73] Assignee: Math. Bauerle GmbH, St. Georgen, Germany [22] Filed: June 29, 1970 211 Appl. No.: 50,438

3,052,465 9/ 1962 David ..27 l 36 1,572,439 2/ 1926 LaBombard et al. ..271/41 2,357,816 9/1944 Flanigan ..271/36 X Primary Examiner-Joseph Wegbreit Assistant Examiner-Bruce 1'1. Stoner, Jr. Attorney-Kelman and Berman [57] ABSTRACT The sheet feeding mechanism for a small oflset duplicating machine has a sheet engaging element axially adjustable on a continuously rotating drive shaft. The engaging part of the ,element has an exposed face arcuately convex about the axis of rotation and two terminal sections offset from the exposed face in opposite circumferential directions. Two carrier parts of the element respectively connect the tenninal sections to the shaft. One of the two carrier parts is sufficiently resilient to permit some radial movement of the associated terminal section under the deforming pressure of a sheet engaged by the exposed face, while the other carrier part is rigid enough to prevent circumferential movement of the entire face.

9 Claims, 5 Drawing Figures Patented March 14, 1972 3,649,003

2 Sheets-Sheet 1 13y: d M

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SHEET FEEDING MECHANISM FOR A SMALL DUPLICATING MACHINE This invention relates to printing and duplicating equipment, and particularly to a sheet feeding device for an office duplicator and similar relatively small apparatus.

It is common practice to feed papers sheets to a small printing or duplicating machine by means of a moving element which frictionally engages the top sheet of a stack of sheets and slides the engaged sheet horizontally from the stack toward grippers of the machine.

The known simple paper feeders of the friction type cannot be used successfully for different grades of paper without adjustment. The coefi'icient of friction between the friction element and paper having a smooth and glossy surface coating is low, and the sheets tend to stick to each other. It is very difficult to adjust a conventional simple function feeder to the proper contact pressure so that it will move the top sheet, and only the top sheet, of a stack of coated paper. Analogous difficulties are encountered when very thin onion skin paper is fed to the grippers of the printing or duplicating machine.

The problem has been solved satisfactorily in industrial printing machines by the provision of suction feeders and of controls for varying the applied vacuum. Vacuum equipment, however, is not economically available in small duplicating machines for office use, and could not be expected to be handled competently by office personnel if it could be made available at reasonable cost.

An object of the invention is the provision of a paper feeder of the friction type which is capable of handling paper sheets of different weight and surface finish without requiring adjustments.

Another object is the provision of a paper feeding mechanism which is so simple in its construction as to have a long useful life without requiring frequent maintenance.

A further object is the provision of a mechanism of the type described which feeds the engaged sheets very precisely to the grippers or other sheet engaging elements of the printing apparatus proper.

With these objects and others in view, as will hereinafter become apparent, the invention, in one of its aspects, provides a sheet feeding mechanism in which a sheet engaging element is mounted on a shaft continuously rotating during operation of the machine, and rotates with the shaft. The sheet engaging part of the element has an exposed face which is arcuately convex about the axis of rotation and two terminal parts offset from the face in opposite circumferential directions. Two carrier parts of the element respectively connect the terminal sections to the shaft, and one of the carrier parts is yieldably resilient to permit movement of the associated terminal section toward the axis of rotation under the deforming pressure of a sheet engaged by the exposed face.

Other features and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood from the following detailed description of preferred embodiments when considered in connection with the appended drawing in which:

FIG. 1 shows operating elements of a sheet feeding mechanism of the invention in side elevational section on the line II in FIG. 2;

FIG. 2 is a top plan view of the sheet feeding mechanism partly shown in FIG. 1;

FIG. 3 illustrates the sheet engaging element of a modified sheet engaging mechanism in side elevation and partly in section on the line IIIIII in FIG. 4;

FIG. 4 shows the device of FIG. 3 in a view taken in the direction of the arrow A in FIG. 3; and

FIG. 5 illustrates the device of FIG. 3 in fragmentary section on the line V-V in FIG. 3.

Referring now to the drawing in detail, and initially to FIGS. 1 and 2, there is seen a shaft 1, journaled in the frame of an office offset machine, not shown, and coupled to the main drive motor of the machine by a motion transmitting train of which only a gear 2 is shown, the gear being fixedly attached to the shaft 1. The shaft 1 therefore rotates continuously as long as the motor is energized.

The engaging element 3 of the illustrated sheet feeding mechanism is fastened to the shaft by a spring clip 4 approximately U-shaped in cross section and extending about substantially more than one half of the shaft circumference. The circumferentially terminal portions 5 of the clip 4 are bent apart and turned over to facilitate mounting and removal of the clip.

The element 3 is constituted in part by a leaf spring 6 of elongated rectangular shape. The two narrow edges of the spring 6 are superimposed and attached to the spring clip 4 by two shoulder rivets 7. The shanks of the rivets project radially from the inner face of the clip into a groove 8 extending over the full length of the shaft 1. The element 3 may therefore be shifted axially of the shaft as may be required for handling sheets of different width.

While the leaf spring 6 is a unitary piece of steel, its several longitudinal portions differ in shape so as to have different resiliency. One edge fastened by the rivets 7 is part of a longitudinal end portion 9 of the spring 6 which spirals away from the axis of rotation in a wide arc of about and has an outer convex face. The other longitudinal end portion 10 of the spring 6 spirals much more steeply away from the axis and has an outer concave face. Where it is farthest from the axis, it is bent back on itself, and therefore is much less resilient than the end portion 9.

The integral portion 11 of the spring 6 which connects the two end portions 9, 10 is approximately circularly arcuate about the axis of rotation in the normal or inoperative condition shown in FIG. 1. It has an outer, adhesively fastened friction facing 12 of abrasive-loaded rubber composition whose exposed convex face has alternating axial ribs and grooves 13. The terminal sections of the spring portion 11 which are circumferentially offset from the facing 12 in opposite directions are thus connected to the shaft 1 and carried by the two spring portions 9 and 10 of which the portion 9 is sufficiently resilient to permit some radial displacement of the friction facing 12 under the pressure of an engaged sheet whereas the portion 10 is rigid enough to prevent circumferential shifting of the facing In its normal operation, the approximately sickle shaped element 3 of the apparatus is located above a paper table 16 on which a stack of sheets 15 is arranged, the table being raised during operation of the machine in a conventional manner to keep the top sheet of the stack within range of the sheet engaging element 3.

It has been found that the aforedescribed sheet feeding mechanism operates smoothly with papers of different surface texture and different weight because of the relatively small resistance of the carrier portion 9 of the spring 6 to movement of the friction facing 12 in a radial direction, coupled with high rigidity in a circumferential direction provided by the carrier portion 10 which ensures accurate feeding. The contact pressure between the facing 12 and the top sheet of the stack 15 need only be very small even with paper having a smooth coating so that the top sheet does not tend to cling to the subjacent sheet in the stack. 7

Obviously, more than one engaging element 3 may be used on the same shaft 1 if the width of the sheet 15 so requires, and the elements may be shifted axially as needed by loosening or disengaging their spring clips 4.

A modified engaging element for use on the shaft 1 shown in FIGS. 1 and 2 is illustrated in FIGS. 3 to 5. It is a unitary casting having the overall approximate sickle shape of the firstdescribed element 3. Its sheet engaging portion 21 extends in a circular arc about the axis of rotation when not deformed by the pressure of an engaged sheet. It is connected by two radially extending integral carrier arms 22, 23 to a hub portion 24 to which a spring clip 4 is attached by means of a shoulder rivet 7, as described with reference to FIGS. 1 and 2.

Trough-shaped recesses 25 are defined in the exposed face of the sheet engaging portion 21 by axial ribs 26 and circumferential ribs. 27 spaced in two perpendicularly intersecting groups in such a manner that the recesses 25 bounded thereby are axially elongated.

The several parts of the element form the walls of a cavity 28 which extends axially through the element so as to reduce the weight of the same. The thickness of the wall formed by the carrier arm 23 is greatly reduced where it approaches the engaging portion 21. The wall thickness of the circumferentially terminal section of the latter adjacent the arm 23 is also reduced so that the sheet engaging portion 21 may be deflected radially inward by the pressure of an engaged sheet about a rigid pivot provided by the carrier arm 22 which also prevents all circumferential displacement of the exposed face of the sheet engaging part 21.

It has been found that the specific illustrated configuration of the recesses 25 imparts to the sheet engaging face an effect similar to that of suction cups, and that a friction facing of the type shown at 12 in FIGS. 1 and 2 may be dispensed with.

It should be understood, of course, that the foregoing disclosure relates only to preferred embodiments of the invention, and that it is intended to cover all changes and modifications of the apparatus of the invention herein chosen for the purpose of the disclosure which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. In a sheet feeding mechanism, in combination:

a. a shaft having an axis;

b. drive means for continuously rotating said shaft about said axis;

0. a sheet engaging element including 1. an engaging part having an exposed face arcuately convex about said axis and two terminal sections offset from said face in opposite circumferential directions, and

2. two carrier parts respectively connecting said terminal sec,ions to said shaft, one of said carrier parts being yieldably resilient and permitting movement of the associated terminal section toward said axis under the deforming pressure of a sheet engaged by said exposed face; and

d. fastening means releasably fastening said sheet engaging element to said shaft for rotation therewith, said fastening means including 1. a spring clip extending about more than one half of the circumference of said shaft in resilient engagement with said shaft, the shaft being formed with a radially directed opening, and

2. a pin member mounted on said clip and extending there-from into said opening for limiting rotary movement of the clip on said shaft.

2. In a mechanism as set forth in claim 1, an elongated leaf spring member having two end portions fastened to said shaft and respectively constituting said carrier parts of the sheet engaging element, and a portion connecting said end portions, said spring member having an approximate sickle-shape, said engaging part including a friction facing secured to said connecting portion of the spring member.

3. In a mechanism as set forth in claim 1, said exposed face being substantially circularly arcuate about said axis in the absence of deforming pressure.

4. In a mechanism as set forth in claim 1, said exposed face being formed with a plurality of alternating projections and recesses.

5. In a mechanism as set forth in claim 4, said recesses being open in a radially outward direction and closed axially and circumferentially by said projections so as to be trough-shaped.

6. In a mechanism as set forth in claim 1, said pin member securing said carrier parts to said spring clip.

7. In a mechanism as set forth in claim 1, said opening being axially elongated and of a length sufficient to permit fastening said sheet engaging element to said shaft in a plurality of axially spaced positions.

8. In a sheet feeding mechanism, in combination:

a. a shaft having an axis;

b. drive means for continuously rotating said shaft about said axis;

0. a sheet engaging element mounted on said shaft for rotation therewith, said element including 1. an engaging part having an exposed face arcuately convex about said axis and two terminal sections offset from said face in opposite circumferential directions, and

2. two carrier parts respectively connecting said terminal sections to said shaft, one of said carrier parts being yieldably resilient and permitting movement of the associated terminal section toward said axis under the deforming pressure of a sheet engaged by said exposed face,

3. said two carrier parts and said engaging part jointly bounding a cavity in said engaging element and constituting walls of said cavity, the wall thickness of said one carrier part being substantially smaller than the wall thickness of the other carrier part.

9. In a mechanism as set forth in claim 8, the terminal section of said engaging part connected to said one carrier part having a wall thickness substantially smaller than the wall thickness of the other terminal section, said other carrier part being sufficiently rigid to prevent circumferential movement of said engaging part when feeding an engaged sheet during rotation of said shaft. 

1. In a sheet feeding mechanism, in combination: a. a shaft having an axis; b. drive means for continuously rotating said shaft about said axis; c. a sheet engaging element including
 1. an engaging part having an exposed face arcuately convex about said axis and two terminal sections offset from said face in opposite circumferential directions, and
 2. two carrier parts respectively connecting said terminal sections to said shaft, one of said carrier parts being yieldably resilient and permitting movement of the associated terminal section toward said axis under the deforming pressure of a sheet engaged by said exposed face; and d. fastening means releasably fastening said sheet engaging element to said shaft for rotation therewith, said fastening means including
 1. a spring clip extending about more than one half of the circumference of said shaft in resilient engagement with said shaft, the shaft being formed with a radially directed opening, and
 2. a pin member mounted on said clip and extending there-from into said opening for limiting rotary movement of the clip on said shaft.
 2. two carrier parts respectively connecting said terminal sections to said shaft, one of said carrier parts being yieldably resilient and permitting movement of the associated terminal section toward said axis under the deforming pressure of a sheet engaged by said exposed face; and d. fastening means releasably fastening said sheet engaging element to said shaft for rotation therewith, said fastening means including
 2. a pin member mounted on said clip and extending there-from into said opening for limiting rotary movement of the clip on said shaft.
 2. In a mechanism as set forth in claim 1, an elongated leaf spring member having two end portions fastened to said shaft and respectively constituting said carrier parts of the sheet engaging element, and a portion connecting said end portions, said spring member having an approximate sickle-shape, said engaging part including a friction facing secured to said connecting portion of the spring member.
 2. two carrier parts respectively connecting said terminal sections to said shaft, one of said carrier parts being yieldably resilient and permitting movement of the associated terminal section toward said axis under the deforming pressure of a sheet engaged by said exposed face,
 3. said two carrier parts and said engaging part jointly bounding a cavity in said engaging element and constituting walls of said cavity, the wall thickness of said one carrier part being substantially smaller than the wall thickness of the other carrier part.
 3. In a mechanism as set forth in claim 1, said exposed face being substantially circularly arcuate about said axis in the absence of deforming pressure.
 4. In a mechanism as set forth in claim 1, said exposed face being formed with a plurality of alternating projections and recesses.
 5. In a mechanism as set forth in claim 4, said recesses being open in a radially outward direction and closed axially and circumferentially by said projections so as to be trough-shaped.
 6. In a mechanism as set forth in claim 1, said pin member securing said carrier parts to said spring clip.
 7. In a mechanism as set forth in claim 1, said opening being axially elongated and of a length sufficient to permit fastening said sheet engaging element to said shaft in a plurality of axially spaced positions.
 8. In a sheet feeding mechanism, in combination: a. a shaft having an axis; b. drive means for continuously rotating said shaft about said axis; c. a sheet engaging element mounted on said shaft for rotation therewith, said element including
 9. In a mechanism as set forth in claim 8, the terminal section of said engaging part connected to said one carrier part having a wall thickness substantially smaller than the wall thickness of the other terminal section, said other carrier part being sufficiently rigid to prevent circumferential movement of said engaging part when feeding an engaged sheet during rotation of said shaft. 